Japanese Patent Application No. 2002-53615, filed on Feb. 28, 2002, is hereby incorporated by reference in its entirety.
The present invention relates to a wiring board and method of manufacturing the wiring board, to an electronic component and to an electronic instrument.
Chip On Film (COF) is a known mounting method, in which a semiconductor chip is mounted on a tape. Wiring patterns are formed on the tape, and also a protective film (for example, a solder resist) is formed covering the wiring patterns. The terminals of the wiring patterns are formed as lands, which are wider than lines. Then the protective film covers and protects the lines and the connections with the lines in the lands, and has an opening for exposing part of the lands except the connections. That is to say, at least part of an end portion of the protective film (having an opening) is provided over the lands.
However, since the adhesion between the protective film (insulating material) and the lands (metal) is weak, the two tend to peel apart. In particular, after the protective film is formed, if plating is applied to the exposed portions of the lands, then plating fluid seeping into the boundary between the protective film and the land may cause the protective film to peel off. If the protective film peels off, the exposed wiring patterns induce electro migration or oxidation, and the reliability of the semiconductor device is impaired.
According to a first aspect of the present invention, there is provided a wiring board comprising:
a substrate;
a wiring pattern which is provided on the substrate and includes a land and a line connected to the land; and
a protective film which has an opening and is provided over the substrate and the wiring pattern, wherein:
the land havs a first portion which includes a connecting portion connected to the line and is covered by the protective film, and a second portion exposed by the opening; and
a hole is formed at least in the first portion of the land, to expose the substrate.
According to a second aspect of the present invention, there is provided an electronic component comprising:
the above-described wiring board; and
an electronic element having a terminal electrically connected to the second portion of the land, and mounted on the wiring board.
According to a third aspect of the present invention, there is provided an electronic instrument comprising the above-described electronic component.
According to a fourth aspect of the present invention, there is provided a method of manufacturing a wiring board, comprising:
forming on a substrate a wiring pattern which has a land and a line connected to the land;
forming a hole in the land for exposing the substrate; and
forming a protective film having an opening to provide on the land a first portion covered by the protective film and including a connecting portion connected to the line and at least part of a portion having the hole, and a second portion exposed by the opening.